Sharif Digital Repository

The reactivity of different carboxylate esters for the Fries rearrangements has been investigated in a solvent-free reaction using sulfated zirconia as a solid acid catalyst  

Phytochemical investigation of the aerial parts of Salvia eremophila led to the isolation of a lupane triterpenoid, 3β, 20-dihydroxylupane-28-oic acid (1), together with eight other compounds, comprising three diterpene, two triterpene, two flavonoids and a steroidal glucoside. Their structures were elucidated by interpretation of their one-dimensional and two-dimensional NMR spectra and completed by the analysis of the HRESIMS data. Compounds 1, 2-4 and 8 were evaluated for their cytotoxicities against five human tumour cell lines. Compounds 1 and 3 hold a good potential for use in future studies due to their anti-cancer properties  

Ultrasound irradiation in presence of 20% ZnBr2 effectively promotes regio-and stereo-selective cycloaddition reaction of azomethine ylide with a series of (E)-3-benzylideneindolin-2-ones to afford 3,3′-dispiropyrrolidine bisoxindole derivatives in excellent yields in methanol at room temperature. The factors affecting the cycloaddition reaction, for example solvent, catalyst, ultrasonic irradiation, are examined in detail to find the mildest conditions and highest reaction yields. The structure and stereochemistry of cycloadducts were determined by spectroscopic data and confirmed by X-ray crystallographic analysis. © ARKAT USA, Inc  

Aryl halides and especially inactive aryl chlorides were coupled to benzenoid aromatic rings in a Suzuki–Miyaura coupling reaction in the absence of organic solvents and toxic phosphine ligands. The reaction was catalysed by a recoverable magnetic nanocatalyst, Pd@Fe3O4, in aqueous media. This method is green, and the catalyst is easily removed from the reaction media using an external magnetic field and can be re-used at least 10 times without any considerable loss in its activity. The catalyst was characterized using scanning and transmission electron microscopies, thermogravimetric analysis, inductively coupled plasma spectroscopy, Fourier transform infrared spectroscopy, CHN analysis,... 

Alkali metal salts of phthalimide-N-oxyl, including Li, Na, and K were prepared and applied as novel selective catalysts to promote the cyclotrimerization of aryl and alkyl isocyanates. This paper is addressing these salts as a new class of organic nucleophilic catalysts. © Springer-Verlag 2006  

Indole-2(3H)thiones were cyclized under the action of 2-fluorobenzoyl chlorides to give thiochromeno[2,3-b]indol-11(6H)-ones or under the action of 2-chloronicotinoyl chlorides to give pyrido[3′,2′:5,6]thiopyrano[2, 3-b]indol-5(10H)-ones. The reaction of cyclization proceeds regioselectively in DMF and does not require transition metals for completion. Obtained heterocycles are isosteric analogues of various tetracyclic indole derived alkaloids  

A manganese(III) complex, [Mn(phox)2(CH3OH) 2]ClO4 (phox = 2-(2′-hydroxyphenyl)oxazoline), was immobilized on silica-coated magnetic Fe3O4 nanoparticles through the amino propyl linkage using a grafting process in dichloromethane. The resulting Fe3O4@SiO2-NH2@Mn(III) nanoparticles are used as efficient and recyclable catalysts for selective oxidation of thiols to disulfides using urea-hydrogen peroxide as the oxidant. The nanocatalyst was recycled several times. Leaching and recycling experiments revealed that the nanocatalyst can be recovered, recycled, and reused more than five times, without the loss of catalytic activity and magnetic properties. The recycling of the nanocatalyst in six... 

The cyclization of cyclohexane-1,3-diones with various substituted pyridinium salts afforded functionalized 8-oxa-10-aza-tricyclo[7.3.1.0 2,7]trideca-2(7),11-dienes. The reaction proceeds by regioselective attack of the central carbon atom of the 1,3-dicar-bonyl unit to 4-position of the pyridinium salt and subsequent cyclization by base-assisted proton migration and nucleophilic addition of the oxygen atom to the 2-position, as was elucidated by DFT computations. Fairly extensive screening of bases and additives revealed that the presence of potassium cations is essential for formation of the product  

The reaction of thiooxindoles with various 2- and 3-substituted pyridinium salts afforded a variety of functionalized thiazocinoindoles. The products have been prepared in good to excellent yields by regioselective dinucleophilic C/S-cyclocondensation of thiooxindoles with pyridinium salts  

The synthesis of pure α-Fe2O3 nanoparticles (30 nm) using a superabsorbent nanopolymer (SANP) by the thermal decomposition is reported. Synthesized α-Fe2O3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electronic microscopy (TEM) and thermogravimetric analysis (TG) techniques. The applicability of this nanostructure material was assessed by its catalytic effect on the Friedel-Crafts acylation. ©2009 Sociedade Brasileira de Química